Abstract: The present study was composed by two papers which aims were: a) to describe the prevalence of dental caries and dental fluorosis in 12-years-old schoolchildren from Piracicaba/SP and Iracemápolis/SP, Brazil, 2007 and to compare current prevalence rates with those from previous epidemiological surveys developed in Piracicaba, for dental caries (1971-2005), and for dental fluorosis (1991-2001) and in Iracemápolis for dental caries and dental fluorosis (1991-2004); b) to evaluate the caries experience and dental fluorosis prevalence in 12-years-old schoolchildren from Piracicaba/SP, Brazil, 2007 and to verify the relationship between these trends, socioeconomic factors, and behavioral variables related to oral health. The sample consisted of 724 schoolchildren from public and private schools from Piracicaba/SP and 197 schoolchildren from public schools from Iracemápolis/SP. Examinations were executed by a previously calibrated examiner, in outdoor settings, under natural light, using dental mirror, CPI probe, and previous tooth brushing, followed the WHO recommendations. Dental caries was measured by DMFT and SiC (Significant Caries Index) indexes and dental fluorosis by T-F index. Socioeconomic variables (monthly income, number of residents in home, mother's and father's education and home ownership) and behavioral information were collected by means of a parental semi structured questionnaire. Then multiple logistic regression analyses using the stepwise procedure were performed in order to verify the relationship among the dependent variables (DMFT and fluorosis) and the independent variables (socioeconomic and behavioral variables). The mean of DMFT was 0.85 (SD=1.54) and 1.02 (SD=1.61) and the SiC Index was 2.52 (SD=1.72) and 2.83 (SD=1.60) in Piracicaba and Iracemápolis, respectively. The fluorosis prevalence was 29.4% and 25.4% in Piracicaba and Iracemápolis, respectively. Comparing the present study to another previous epidemiological surveys, in both towns, a significant caries reduction of 90.12% (Piracicaba) and of 85.07% (Iracemápolis) (p<0.01), have been observed. Concerning dental fluorosis prevalence, an increase of 44.1% was noted in Piracicaba, where a small prevalence was observed throughout the years. Although, the increase was 1170% in Iracemápolis. By means of multiple logistic regression model, children, whose family earned up to four minimum wages, were 2.58 more prone to have caries (DMFT>0) than those whose family earned over four minimum wages. Besides, those children who visited the dentist were 4.27 more prone of being diagnosed with dental caries and receive treatment in comparison to those who never had visited the dentist. However, for fluorosis prevalence the multiple logistic regression model was not significant. In conclusion, the results of this thesis demonstrated continuous decrease in dental caries experience in both Brazilian towns. Concerning dental fluorosis, stabilization trends were observed in Piracicaba. In Iracemápolis, however, a constant increase was noted. Moreover, significant associations between the presence of dental caries and monthly family income, as well as between dental caries and visiting to the dentist, were observed. However, in relation to dental fluorosis, no tested variable was associated with the disturb